1. Technical Field
The present invention relates to automotive vehicles running on ball-bearing casters, and in particular to electrically driven wheelchair vehicles employing ball-bearing casters as wheels.
2. Description of Related Art
Electrically driven wheelchairs as vehicles for the welfare of the elderly or ambulatory-impaired are universally in use. Such wheelchairs are designed to be omnidirectionally mobile; an example of a wheelchair thus constituted is illustrated in FIGS. 7 and 8.
As shown therein, four wheel assemblies 92 are installed in the lower portion of a main body 91 of a wheelchair 90. Each wheel assembly 92 comprises a change-direction axle 92a pivotally fitted onto the underside of the wheelchair main body 91, a fixed base 92b fixed to the lower end of the change-direction axle 92a, a wheel support 92c extending down from the stationary base 92b, a wheel 92d supported on the wheel support 92c, and a drive motor 92e mounted on the fixed base 92b for driving the wheel 92d to rotate. To change the orientation of the wheel assemblies 92, the change-direction axles 92a are pivoted by means of a change-direction motor 93. Accordingly, the wheelchair 90 is mobile in any direction.
In general, then, wheelchairs such as the wheelchair 90 and like vehicles for the welfare of the elderly and disabled will employ a change-direction motor separately from the drive motor.
In this regard, there would be cost benefits to a wheelchair that can both be driven and change direction by a single motor.
Further, from a structural standpoint, with conventional vehicles such as the foregoing wheelchair 90, wherein the running direction is to be switched, it is necessary to stop the vehicle momentarily and change the orientation of the wheels. There is a time lag between the direction-changing operation and the moment the direction is actually changed. In other words, in such conventional vehicles the control responsiveness with regard to direction-switching is low.